Solenoid

ABSTRACT

Provided is a solenoid which is easier to assemble and which is improved in terms of operability. The solenoid is provided with a snap ring  22  which helps to integrate the molded coil  2  and the solenoid main body  3  into one, whereby it is possible to finally integrate the molded coil  2  and the solenoid main body  3  with each other after various operation processes; by finally attaching the molded coil  2 , the lead wire  9  extending from the molded coil  2  constitutes no obstacle, and the assembly is facilitated, thus achieving an improvement in terms of operability.

This is a nationalization of PCT/JP02/13672 filed Dec. 26, 2002 andpublished in Japanese.

TECHNICAL FIELD

The present invention relates to a solenoid for use in solenoid valvesor the like for various types of hydraulic/pneumatic control apparatusessuch as a shock absorber.

BACKGROUND ART

FIG. 13 shows an example of a conventional solenoid of this type. FIG.13 is a schematic sectional view of a conventional solenoid.

A solenoid 101 is formed by combining a molded coil 102 and a solenoidmain body 103 with each other into an integral unit.

The molded coil 102 includes a coil 104 wound around thereon, and, atthe center of the coil 104, there is formed a hole 105 recessed facingthe solenoid main body 103.

Further, in the portion of the molded coil 102 on the side opposite tothe solenoid main body 103, there is provided an annular plate 106 whichis adjacent to the coil 104, and, from the plate 106 onward, there isprovided a mold portion 107 forming the bottom surface of the hole 105.In the mold portion 107, a coil wire 108 led out of the coil 104 isconnected to a lead wire 109.

The solenoid main body 103 is equipped with a column portion 110 whichconstitutes a core portion thereof and which is to be inserted into thehole 105 of the molded coil 102, and a case 111 spaced apart from thecolumn portion 110 through the intermediation of the annular space inwhich the molded coil 102 is arranged and covering the outer peripheryof the molded coil 102.

The column portion 110 of the solenoid main body 103 is equipped withcenter post 112 formed integrally with the case 111, a plunger 113magnetically attracted to the center post 112 through energization ofthe coil 104, a rod 114 connected to the plunger 113, a bearing 115supporting the rod 114, a cap 116 covering the forward end portion ofthe column portion 110, and a guide 117 smoothening the outer peripherybetween the cap 116 and the center post 112 to facilitate the insertionof the column portion 110 into the hole 105 of the molded coil 102.

A shim 118 is arranged on the inner side of the center post 112.

The center post 112 extends from the inner end of an annular radialportion 119 toward the molded coil 102. Further, the case 111 alsoextends from the outer end of the annular radial portion 119 toward themolded coil 102.

And, caulking fixation is effected on the end portion of the case 111and the corner portion of the molded coil 102, whereby the molded coil102 and the solenoid main body 103 are integrated with each other.

In the solenoid 101, constructed as described above, by supplyingelectric current to the coil 104 through the lead wire 109, a magneticcircuit is formed, where a current passes through: the center post 112,the case 111, the plate 106, and the plunger 113, and back to 112. Theplunger 113 is magnetically attracted to the center post 112.

When no electric current is being supplied to the coil 104, the plunger113 is spaced apart from the center post 112 as shown in the drawingunder the urging force of a spring or the like (not shown).

However, in this conventional solenoid 101, in which the molded coil 102and the solenoid main body 103 are integrated with each other bycaulking fixation, the presence of the lead wire 109 constitutes anobstacle when the solenoid 101 is mounted to an associatedhydraulic/pneumatic control apparatus, resulting in a rather poormounting operability.

Further, in the assembly line for assembling the hydraulic/pneumaticcontrol apparatus concerned, the presence of the lead wire 109constitutes an obstacle even in the process after the mounting of thesolenoid 101 to the hydraulic/pneumatic control process, resulting in arather poor operability.

Further, when the solenoid 101, composed of the molded coil 102 and thesolenoid main body 103 integrated with each other through caulkingfixation, is mounted to the associated hydraulic/pneumatic controlapparatus by welding, heat load is applied to the molded coil 102, whichentails the need for special consideration during operation. Otherwise,welding cannot be selected as the mounting method.

And, in an apparatus involving coating as in the case of a shockabsorber, coating is first performed separately on the apparatus and thecase 111 of the solenoid main body 103, and then the molded coil 102 andthe solenoid main body 103 are integrated into one through caulkingfixation. Thereafter, the solenoid 101, formed into an integral unit, ismounted to the apparatus, which means coating has to be performedseparately on the apparatus and the case 111, resulting in a rather pooroperability.

DISCLOSURE OF THE INVENTION

The present invention has been made with a view toward solving the aboveproblems in the conventional art. It is an object of the presentinvention to provide a solenoid which is easier to assemble and which isimproved in terms of operability.

To achieve the above object, there is provided, in accordance with thepresent invention, a solenoid in which it is possible to mount solelythe solenoid main body to the associated hydraulic/pneumatic controlapparatus prior to the integration of the molded coil and the solenoidmain body into a unit, in which, after the mounting of the solenoid mainbody, the molded coil and the solenoid main body are finally integratedwith each other after various operation processes before being mountedto the hydraulic/pneumatic control apparatus.

Thus, the lead wire extending from the molded coil does not constituteany obstacle to the assembly operation. Further, it is possible toperform the welding of the solenoid main body to the hydraulic/pneumaticcontrol apparatus beforehand, so that no heat load is applied to themolded coil. Further, in an apparatus involving coating as in the caseof a shock absorber, it is possible to mount the solenoid main body tothe apparatus beforehand, and then to perform coating collectively onthe apparatus and the case of the solenoid main body.

Therefore, according to the present invention, there is provided asolenoid including:

a molded coil composed of a coil of a plural number of turns and havinga hole at its center; and

a solenoid main body having a case covering the outer periphery of themolded coil, a movable plunger inserted into the hole at the center ofthe molded coil, and a center post arranged in a direction in which theplunger is moved and attracted by a magnetic force generated by thecoil,

characterized in that a snap ring is provided for integrating the moldedcoil and the solenoid main body into one.

It is preferable that the snap ring is mounted between a step portion inthe outer periphery of the molded coil and a groove formed in the innerperipheral surface of the case.

It is preferable that the snap ring is mounted between a groove formedin the outer peripheral surface of the molded coil and a groove formedin the inner peripheral surface of the case.

It is preferable that the outer diameter of the molded coil as measuredat least on the outer side of the position where the snap ring ismounted is substantially the same as the inner diameter of the case.

It is preferable that a peripheral section of the bottom of a grooveformed in the outer peripheral surface of the molded coil and aroundwhich the snap ring is wrapped is noncircular.

It is preferable that a wall portion is provided which protrudes fromthe bottom of the groove formed in the outer peripheral surface of themolded coil and around which the snap ring is wrapped and whichconstitutes a stopping between the end portions of the snap ring.

It is preferable that a protrusion is provided which is spaced apartfrom the bottom of the groove formed in the outer peripheral surface ofthe molded coil and around which the snap ring is wrapped and which issituated on the outer side of the portion between the end portions ofthe snap ring.

According to the present invention, there is provided a solenoidincluding:

a molded coil composed of a coil of a plural number of turns and havinga hole at its center; and

a solenoid main body having a case covering the outer periphery of themolded coil, a movable plunger inserted into the hole at the center ofthe molded coil, and a center post arranged in a direction in which theplunger is moved and attracted by a magnetic force generated by thecoil,

characterized in that an engagement portion is provided for engaging themolded coil and the case with each other so as to integrate the moldedcoil and the solenoid main body into one.

It is preferable that the engagement portion is composed of a recessprovided in one of the molded coil and the case and a protrusion lockedthe recess and provided on the other of the molded coil and the case.

In accordance with the present invention, there is provided a snap ringwhich helps to integrate the molded coil and the solenoid main body intoone, whereby it is possible to finally integrate the molded coil and thesolenoid main body with each other after various operation processes; byfinally attaching the molded coil, the lead wire extending from themolded coil constitutes no obstacle, and the assembly is facilitated,thus achieving an improvement in terms of operability.

By mounting the snap ring between the step portion in the outerperiphery of the molded coil and the groove formed in the innerperipheral surface of the case, it is possible to first fit the snapring into the groove formed in the inner peripheral surface of the case,and then put the molded coil in the case for integration, therebyfacilitating the assembly and achieving an improvement in the assemblingperformance.

By mounting the snap ring between the groove formed in the outerperipheral surface of the molded coil and the groove formed in the innerperipheral surface of the case, it is possible to first fit the snapring into the groove formed in the outer peripheral surface of themolded coil, and then put the molded coil with the snap ring fittedtherein in the case for integration, thereby facilitating the assemblyand achieving an improvement in the assembling performance.

Since the outer diameter of the molded coil as measured at least on theouter side of the position where the snap ring is mounted issubstantially the same as the inner diameter of the case, there is nogap between the molded coil and the case outside the position where thesnap ring is mounted, and the snap ring is invisible from outside, sothat the user cannot touch the snap ring, thereby achieving animprovement in terms of safety.

The peripheral section of the bottom of the groove formed in the outerperipheral surface of the molded coil, around which the snap ring iswrapped, is noncircular, which allows centering of the snap ring andmakes it possible to make the outer diameter of the portion where thecoil and the lead wire are connected through the coil wire relativelylarge in order to secure the requisite wall thickness for thecorresponding portion of the mold portion. Further, in the noncircularouter periphery in conformity with the configuration of the snap ring,no great insertion load is applied to the solenoid main body of themolded coil around which the snap ring is wrapped, thus achieving animprovement in the mounting performance.

Further, after the completion of the assembly, the molded coil is notallowed to rotate freely, so that it is possible to prevent stress frombeing applied to the lead wire. Thus, there is no fear of the lead wirebeing pulled, twisted, etc. as a result of rotation of the molded coil,thus stabilizing the attitude of the molded coil.

Due to the provision of the wall portion protruding from the bottom ofthe groove formed in the outer peripheral surface of the molded coilaround which the snap ring is wrapped and constituting a stoppingbetween the end portions of the snap ring, it is possible to prevent thesnap ring from being rotated since either end portion of the snap ringabuts the wall portion, so that it is possible to prevent the snap ringfrom being displaced from the proper position to thereby constitute suchan obstruction as would make it impossible to put the molded coil in thecase.

Due to the provision of the protrusion spaced apart from the bottom ofthe groove which is formed in the outer peripheral surface of the moldedcoil and around which the snap ring is wrapped, and situated on theouter side of the portion between the end portions of the snap ring, itis possible to prevent the snap ring from rotating since either endportion of the snap ring abuts the protrusion. Further, even when eitherend portion of the snap ring abuts the protrusion, the snap ring can becontracted from both sides, so that no increase in the requisite forcefor contracting the snap ring is involved.

Due to the provision of the engagement portion for engagement of themolded coil and the case with each other so as to integrate the moldedcoil and the solenoid main body into one, the molded coil and thesolenoid main body can be easily integrated finally after variousoperation processes; by finally attaching the molded coil, the lead wireconstitutes no obstacle upon the assembly, thus simplifying the assemblyand achieving an improvement in the assembling performance.

The engagement portion is composed of a recess provided in one of themolded coil and the case and a protrusion locked the recess and providedon the other of these components, whereby it is possible to realize anintegrated unit composed of the molded coil and the solenoid main bodyin a simple construction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a solenoid according to a firstembodiment.

FIG. 2 is a schematic sectional view of the components of the solenoidof the first embodiment.

FIG. 3 is a schematic sectional view taken along the line a—a of FIG. 1.

FIG. 4 is a schematic sectional view of a solenoid according to a secondembodiment.

FIG. 5 is a schematic sectional view of the components of the solenoidof the second embodiment.

FIG. 6 is a schematic sectional view taken along the line a—a of FIG. 4.

FIGS. 7 are schematic sectional views taken along the line a—a of FIG.4.

FIGS. 8 are schematic sectional views taken along the line a—a of FIG.4.

FIG. 9 is a schematic sectional view of a solenoid according to a sixthembodiment.

FIG. 10 is a schematic sectional view of a solenoid according to aseventh embodiment.

FIG. 11 is a schematic sectional view of a solenoid according to aneighth embodiment.

FIG. 12 is a schematic sectional view of a solenoid according to a ninthembodiment.

FIG. 13 is a schematic sectional view of a conventional solenoid.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of this invention will now be described in detailwith reference to the drawings. Note that the dimensions, materials,configurations, and positional relationship of the components of theseembodiments as given below should not be construed restrictively unlessotherwise specified.

(First Embodiment)

A solenoid according to a first embodiment of the present invention willbe described with reference to FIGS. 1 through 3. FIG. 1 is a schematicsectional view of the solenoid of the first embodiment. FIG. 2 is aschematic sectional view of the components of the solenoid of the firstembodiment. FIG. 3 is a schematic sectional view taken along the linea—a of FIG. 1.

A solenoid 1 is formed by integrating a molded coil 2 and a solenoidmain body 3 with each other.

The molded coil 2 includes a wound-up coil 4, at the center of whichthere is formed a hole 5 facing the solenoid main body 3.

Further, in a portion of the molded coil 2 on the side opposite to thesolenoid main body 3, there is provided an annular plate 6 adjacent tothe coil 4. From the plate 6 onward, there is provided a mold portion 7forming a bottom surface of the hole 5. In the mold portion 7, a coilwire 8 led out of the coil 4 is connected to a lead wire 9.

The solenoid main body 3 is equipped with a column portion 10 which issituated at the axial center thereof and which is to be inserted intothe hole 5 of the molded coil 2 and a case 11 spaced apart from thecolumn portion 10 through the intermediation of an annular space, inwhich the molded coil 2 is arranged, and covering the outer periphery ofthe molded coil 2.

The column portion 10 of the solenoid main body 3 is equipped with acenter post 12 formed integrally with the case 11, a plunger 13magnetically attracted to the center post 12 through energization of thecoil 4, a rod 14 connected to the plunger 13, a bearing 15 supportingthe rod 14, a cap 16 covering the forward end portion of the columnportion 10, and a guide 17 smoothening the outer periphery between thecap 16 and the center post 12 to facilitate the insertion of the columnportion 10 into the hole 5 of the molded coil 2.

A shim 18 is arranged on the inner side of the center post 12.

The center post 12 extends toward the molded coil 2 side from the innerend of an annular radial portion 19. Further, the case 11 also extendstoward the molded coil 2 side from the outer end of the annular radialportion 19.

Then, a snap ring 22 is mounted between a groove 20 formed in the innerperipheral surface of the case 11 and a step portion 21 formed in theouter periphery of the molded coil 2. By thus mounting the snap ring 22,the molded coil 2 and the solenoid main body 3 are integrated into one.

As shown in FIG. 3, which is a sectional view taken along the line a—aof FIG. 1, in the solenoid 1 of this embodiment, the peripheral sectionof the bottom of the groove around which the snap ring 22 is wrapped iscircular.

In the solenoid 1 constructed as described above, by supplying anelectric current to the coil 4 through the lead wire 9, a magneticcircuit is formed by the center post 12, the case 11, the plate 6, andthe plunger 13, with the plunger 13 being magnetically attracted to thecenter post 12.

When no electric current is being supplied to the coil 4, the plunger 13is spaced apart from the center post 12 as shown in the drawing underthe urging force of a spring or the like (not shown).

In this solenoid 1, in the state in which, as shown in FIG. 2, themolded coil 2, the solenoid main body 3, and the snap ring 22 areseparated from each other, the molded coil 2 is first put in the case11. Then, thereafter, the snap ring 22 is fitted into the groove 20formed in the inner peripheral surface of the case 11, and the snap ring22 is hooked onto the step portion in the outer periphery of the moldedcoil 2 to thereby mount the snap ring, whereby the molded coil 2 and thesolenoid main body 3 can be integrated into one, thus facilitating theassembly and achieving an improvement in the assembling performance.

Further, in this embodiment, around the portions of the molded coil 2and the case 11 where the snap ring 22 is fitted, there is a differencebetween the outer diameter of the molded coil 2 and the inner diameterof the case 11.

Thus, in the portions of the molded coil 2 and the case 11 where thesnap ring 22 is fitted, there is a gap between the molded coil 2 and thecase 11, and the snap ring 22 is visible from outside, so that it ispossible to touch the snap ring 22 and remove it easily, therebyachieving an improvement in terms of maintainability.

(Second Embodiment)

A solenoid according to a second embodiment of the present inventionwill be described with reference to FIGS. 4 and 5. FIG. 4 is a schematicsectional view of the solenoid of the second embodiment. FIG. 5 is aschematic sectional view of the components of the solenoid of the secondembodiment. The components which are the same as those of theabove-described embodiment are indicated by the same reference numerals,and a description of such components will be omitted.

In the solenoid 1 of this embodiment, the snap ring 22 is mountedbetween the groove 20 formed in the inner peripheral surface of the case11 and a groove 23 formed in the outer periphery of the molded coil 2.Due to the mounting of this snap ring 22, the molded coil 2 and thesolenoid main body 3 are integrated into one.

As shown in FIG. 3, which is a sectional view taken along the line a—aof FIG. 4, as in the case of the first embodiment, in the solenoid 1 ofthis embodiment, the peripheral section of the bottom of the groove 23of the molded coil 2, around which the snap ring 22 is wrapped, iscircular.

In this solenoid 1, in the state in which the molded coil 2, thesolenoid main body 3, and the snap ring 22 are separated from each otheras shown in FIG. 5, the snap ring 22 is first fitted into the groove 23formed in the outer peripheral surface of the molded coil 2. Then,thereafter, the molded coil 2 is put in the case 11, and the snap ring22 is also fitted into the groove 20 formed in the inner peripheralsurface of the case 11 to thereby mount the snap ring 22, whereby it ispossible to integrate the molded coil 2 and the solenoid main body 3into one, thereby facilitating the assembly and achieving an improvementin the assembling performance.

Further, in this embodiment, around the portions of the molded coil 2and the case 11 where the grooves 23 and 20, into which the snap ring 22is to be fitted, are formed, the outer diameter of the molded coil 2 andthe inner diameter of the case 11 are substantially the same.

Thus, in the portions of the molded coil 2 and the case 11 where thegrooves 23 and 20, into which the snap ring 22 is to be fitted, are notformed, there is no gap between the molded coil 2 and the case 11, andthe snap ring 22 is not visible from outside, so that the user cannottouch the snap ring 22, thereby achieving an improvement in terms ofsafety.

When the portion where there is no gap between the molded coil 2 and thecase 11, that is, the portion where the outer diameter of the moldedcoil 2 and the inner diameter of the case 11 are substantially the same,is formed at least on the outer side of the position where the snap ring22 is mounted, the snap ring 22 is not visible from outside, thus makingit possible to achieve the above objective.

Further, an improvement in terms of assembling performance can beachieved even if the portion where the outer diameter of the molded coil2 and the inner diameter of the case 11 are substantially the same isnot formed at least on the outer side of the portion where the snap ring22 is mounted.

(Third Embodiment)

A solenoid according to a third embodiment of the present invention willbe described with reference to FIG. 6. FIG. 6 is a schematic sectionalview similar to FIG. 3, which is taken along the line a—a of FIG. 4. Thecomponents which are the same as those of the above-describedembodiments are indicated by the same reference numerals, and adescription of such components will be omitted.

In the second embodiment, to allow centering of the snap ring 22, it isnecessary for the outer diameter of the groove 23 of the molded coil 2to be large to some degree. However, making the outer diameter largeresults in an increase in the insertion load for the molded coil 2 withthe snap ring 22 attached thereto, which entails a problem regarding theassembling performance. On the other hand, making the outer diametersmall in order to reduce the insertion load entails a problem regardingthe centering of the snap ring 22 and difficulty in securing therequisite wall thickness of the portion of the mold portion 7 where thecoil 4 and the lead wire 9 are connected through the coil wire 8.

Thus, it has been rather difficult to appropriately set the outerdiameter of the periphery of the bottom of the groove 23 of the moldedcoil 2 around which the snap ring 22 is wrapped.

Further, when the peripheral section of the bottom of the groove 23 ofthe molded coil 2 around which the snap ring 22 is wrapped is circularas shown in FIG. 3, the molded coil 2 is allowed to freely rotate afterthe completion of the solenoid; rotation of the molded coil 2 causes thelead wire 9 to be pulled, twisted, etc., resulting in stress beingapplied to the lead wire 9.

In view of this, in the solenoid 1 of this embodiment, as shown in FIG.6, which is a sectional view taken along the line a—a of FIG. 4, theperipheral section of the bottom of the groove 23 of the molded coil 2around which the snap ring 22 is wrapped is noncircular.

More specifically, as shown in FIG. 6, the noncircular configuration ofthe peripheral section of the bottom of the groove 23 of the molded coil2 is as follows provided that the contraction of the snapping 22 is nothindered: in conformity with the snap ring 22 fitted into the groove 20of the case 11 which is equally divided into three portions, the groove23 exhibits a relatively large diameter in the portions thereof wherethe snap ring 22 is fitted into the groove 20 of the case 11, and arelatively small diameter in the other portions thereof; in applying aforce to the end portions of the snap ring 22, reducing (enlarging) thediameter of the snap ring 22 results in a reduction (an increase) in thesize of the portion of the snap ring 22 around the end portions thereof;the farther away from the end portions of the snap ring 22, the less thedeformation thereof, thus providing a configuration in conformity withthe permissible deformation of the snap ring 22.

Thus, to allow centering of the snap ring 22 and to secure the requisitewall thickness for the portion of the mold portion 7 where the coil 4and the lead wire 9 are connected through the coil wire 8, it ispossible for the outer diameter of the corresponding portion to be madelarge to some degree, and, in the case of the noncircular outerperiphery in conformity with the configuration of the snap ring 22, noincrease in insertion load is involved for the molded coil 2 with thesnap ring 22 attached thereto, thus improving the assemblingperformance. It has been experimentally ascertained that the insertionload is 294N in the case of the circular peripheral section of thebottom of the groove of the conventional solenoid, whereas it reduces to49N in the case of the noncircular peripheral section of thisembodiment.

Further, after the completion of the solenoid, the molded coil 2 is notallowed to freely rotate, so that there is no fear of the lead wire 9being pulled, twisted, etc. as a result of rotation of the molded coil2, whereby it is possible to prevent stress from being applied to thelead wire 9, thereby stabilizing the attitude of the molded coil 2.

(Fourth Embodiment)

A solenoid according to a fourth embodiment of the present inventionwill be described with reference to FIG. 7. FIG. 7 is a schematicsectional view similar to FIG. 6, which is taken along the line a—a ofFIG. 4. The components which are the same as those of theabove-described embodiments are indicated by the same referencenumerals, and a description of such components will be omitted.

In the third embodiment, the peripheral section of the bottom of thegroove 23 of the molded coil 2 around which the snap ring 22 is wrappedis noncircular. However, when the snap ring 22 attached to the moldedcoil 2 is allowed to rotate before the latter is put in the case 11, thesnap ring 22 is displaced from the proper position to thereby constitutean obstacle, making it impossible to put the molded coil 2 in the case11.

In view of this, in the solenoid 1 of this embodiment, as shown in FIG.7, which is a sectional view taken along the line a—a of FIG. 4, thereis provided a wall portion 7 a protruding from the bottom of the groove23 of the molded coil 2 around which the snap ring 22 is wrapped andconstituting a stopping between the end portions of the snap ring 22.

The wall portion 7 a is provided on the mold portion 7 and constitutes astopping between the end portions of the snap ring 22 to serve as adetent for preventing the snap ring 22 from rotating around the groove23 of the molded coil 2.

In the state shown in FIG. 7A, the portion of the snap ring 22 aroundthe end portions thereof is contracted so as to allow fitting into thecase 11. The deformation into the state shown in FIG. 7A from the stateshown in FIG. 7B is effected by contracting the portions of the snapring 22 around its end portions as indicated by the arrows.

Due to this construction, either end portion of the snap ring 22 abutsthe wall portion 7 a to prevent the snap ring 22 from rotating, makingit possible to prevent the snap ring 22 from being displaced from theproper position to thereby constitute such an obstacle as would make itimpossible to put the molded coil 2 in the case 11.

(Fifth Embodiment)

A solenoid according to a fifth embodiment of the present invention willbe described with reference to FIG. 8. FIG. 8 is a schematic sectionalview similar to FIG. 7, which is taken along the line a—a of FIG. 4. Thecomponents which are the same as those of the above-describedembodiments are indicated by the same reference numerals, and adescription of such components will be omitted.

In the fourth embodiment, there is provided the wall portion 7 aprotruding from the bottom of the groove 23 of the molded coil 2 aroundwhich the snap ring 22 is wrapped and constituting a stopping betweenthe end portions of the snap ring 22. However, an attempt to contractthe portion of the snap ring 22 around the end portions thereof in astate in which one end portion of the snap ring is in contact with thewall portion 7 a as shown in FIG. 7C, results in the contraction beingeffected solely from the side of the other end portion which is out ofcontact with the wall portion 7 a, which leads to the need for a forceof a corresponding magnitude. Further, the snap ring 22 has to be setshorter by the thickness of the wall portion 7 a, with the result thatthe snap ring 22 is liable to rotate.

In view of this, as shown in FIG. 8, which is a sectional view takenalong the line a—a of FIG. 4, in the solenoid 1 of this embodiment,there is provided a protrusion 7 b spaced apart from the bottom of thegroove 23 of the molded coil 2 around which the snap ring 22 is wrappedand situated on the outer side of the portion between the end portionsof the snap ring 22.

The protrusion 7 b is provided on the mold portion 7 and situated in theouter periphery and between the end portions of the snap ring 22 andserves as a detent for preventing the snap ring 22 from rotating aroundthe molded coil 2.

In the state shown in FIG. 8A, the portion of the snap ring 22 aroundthe end portions thereof is contracted so as to allow fitting into thecase 11. The deformation into the state shown in FIG. 8A from the stateshown in FIG. 8B is effected by contracting the portion of the snap ring22 around its end portions as indicated by the arrows.

Also in the case in which the portion of the snap ring 22 around the endportions thereof is to be contracted in the state in which one endportion thereof is in contact with the protrusion 7 b as shown in FIG.8C, it is possible to contract the portion of the snap ring 22 aroundits end portions as indicated by the arrows. As compared with the casein which one end of the snap ring 22 abuts the wall portion 7 a as shownin FIG. 7, the requisite force is smaller.

Thus, it is possible to contract the portion of the snap ring 22 aroundits end portions with a small force and attach the case 11 smoothly.Further, after the attachment of the case 11, rotation of the snap ring22 relative to the molded coil 2 can be reliably prevented.

Furthermore, like the case in which an end portion of the snap ring 22abuts the wall portion 7 a, there is no fear of a sharp-edged portion ofthe end portion of the snap ring 22 cutting into the wall portion 7 a tothereby hinder smooth contraction of the snap ring 22.

Due to the above arrangement, an end portion of the snap ring 22 abutsthe protrusion 7 b to thereby prevent rotation of the snap ring 22, and,even when an end portion of the snap ring 22 abuts the protrusion 7 b,it is possible for the snap ring 22 tope contracted from both sides, sothat no increase in the requisite force for the contraction of the snapring 22 is involved.

(Sixth Embodiment)

A solenoid according to a sixth embodiment of the present invention willbe described with reference to FIG. 9. The components which are the sameas those of the above-described embodiments are indicated by the samereference numerals and a description of such components will be omitted.As shown in FIG. 9, in this embodiment, the solenoid main body 3 ismounted to the associated apparatus 30.

In this embodiment, a recess 24 formed in the inner peripheral surfaceof the case 11 and a protrusion 25 formed in the outer periphery of themolded coil 2 are engaged with each other, whereby the molded coil 2 andthe solenoid main body 3 are integrated into one. That is, the case 11and the molded coil 2 are equipped with an engagement portion composedof the recess 24 and the protrusion 25.

The recess 24 is formed as a through-hole extending from the innerperipheral surface to the outer peripheral surface of the case 11.

The protrusion 25 has a resilient axial portion at its base. The outerdiameter of the axial portion of the protrusion 25 and the innerdiameter of the case 11 are substantially equal to each other.

In this solenoid 1, the molded coil 2 is put in the case 11 in the statein which the molded coil 2 and the solenoid main body 3 are separatedfrom each other, and the protrusion 25 is locked the recess 24, makingit possible to integrate the molded coil 2 and the solenoid main body 3into one, thus facilitating the assembly and achieving an improvement inthe assembling performance.

Further, in this embodiment, the recess 24 is in the form of athrough-hole extending to the outer peripheral surface of the case 11,so that it is possible to push in the protrusion 25 from the outerperipheral surface of the case 11 even in the state in which theprotrusion 25 is locked the recess 24, whereby it is possible to cancelthe engagement of the recess 24 and the protrusion 25, making itpossible to easily separate the molded coil 2 and the solenoid main body3 from each other again. Accordingly, an improvement in terms ofmaintainability can be attained.

(Seventh Embodiment)

A solenoid according to a seventh embodiment of the present inventionwill be described with reference to FIG. 10. The components which arethe same as those of the above-described embodiments are indicated bythe same reference numerals and a description of such components will beomitted. As shown in FIG. 10, in this embodiment, the solenoid main body3 is mounted to the associated apparatus 30.

As in the sixth embodiment, in this embodiment, there is provided theengagement portion composed of the recess 24 and the protrusion 25.

The recess 24 is formed by outwardly hollowing the inner peripheralsurface of the case 11.

Further, the protrusion 25 has a resilient axial portion at its base.The outer diameter of the axial portion of the protrusion 25 and theinner diameter of the case 11 are substantially equal to each other.

In this solenoid 1, the molded coil 2 is put in the case 11 in the statein which the molded coil 2 and the solenoid main body 3 are separatedfrom each other, and the protrusion 25 is locked the recess 24, makingit possible to integrate the molded coil 2 and the solenoid main body 3into one, thus facilitating the assembly and achieving an improvement inthe assembling performance.

In this embodiment, the recess 24 is not formed so as to extend to theouter peripheral surface of the case 11, so that, in the state in whichthe protrusion 25 is locked the recess 24, it is impossible to cancelthe engagement of the recess 24 and the protrusion 25, thereby achievingan improvement in terms of safety.

(Eighth Embodiment)

A solenoid according to an eighth embodiment of the present inventionwill be described with reference to FIG. 11. The components which arethe same as those of the above-described embodiments are indicated bythe same reference numerals and a description of such components will beomitted. As shown in FIG. 11, in this embodiment, the solenoid main body3 is mounted to the associated apparatus 30.

As in the sixth and seventh embodiments, in this embodiment, there isprovided the engagement portion composed of the recess 24 and theprotrusion 25.

The recess 24 is formed by outwardly hollowing the inner peripheralsurface of the case 11. Then, by thus reducing the wall thickness of theportion of the case 11 which the outside of the recess 24, resiliency isimparted thereto.

The protrusion 25 protrudes from a step portion in the outer peripheryof the molded coil 2.

In this solenoid 1, the molded coil 2 is put in the case 11 in the statein which the molded coil 2 and the solenoid main body 3 are separatedfrom each other, and the protrusion 25 is locked the recess 24, makingit possible to integrate the molded coil 2 and the solenoid main body 3into one, thus facilitating the assembly and achieving an improvement interms of the assembling performance.

Further, in this embodiment, there is a gap between the outer side ofthe protrusion 25 and the inner peripheral surface of the case 11, sothat, even in the state in which the protrusion 25 is locked the recess24, it is possible to spread out the end portion of the case 11 tothereby cancel the engagement of the recess 24 and the protrusion 25,and the molded coil 2 and the solenoid main body 3, which have beenintegrated into one, can be again separated from each other easily,thereby achieving an improvement in terms of maintainability.

(Ninth Embodiment)

A solenoid according to a ninth embodiment of the present invention willbe described with reference to FIG. 12. The components which are thesame as those of the above-described embodiments are indicated by thesame reference numerals and a description of such components will beomitted. As shown in FIG. 12, in this embodiment, the solenoid main body3 is mounted to the associated apparatus 30.

As in the sixth to eighth embodiments, in this embodiment, there isprovided the engagement portion composed of the recess 24 and theprotrusion 25.

The recess 24 is formed by outwardly hollowing the inner peripheralsurface of the case 11. And, by thus reducing the wall thickness of theportion of the case 11 where the outside of the recess 24, resiliency isimparted thereto.

Further, the protrusion 25 protrudes from a midpoint of the outerperipheral surface of the molded coil 2. And, the outer diameter of themolded coil 2 and the inner diameter of the case 11 are substantiallythe same.

In this solenoid 1, the molded coil 2 is put in the case 11 in the statein which the molded coil 2 and the solenoid main body 3 are separatedfrom each other, and the protrusion 25 is locked the recess 24, makingit possible to integrate the molded coil 2 and the solenoid main body 3into one, thus facilitating the assembly and achieving an improvement inthe assembling performance.

Further, in this embodiment, in which the outer diameter of the moldedcoil 2 and the inner diameter of the case 11 are substantially the same,there is no gap between these components, so that it is impossible tospread out the end portion of the case 11 in the state in which theprotrusion 25 is locked the recess 24, which means, in this state, it isimpossible to cancel the engagement of the recess 24 and the protrusion25, thereby achieving an improvement in terms of safety.

Note that, while in the sixth through ninth embodiments the recess 24 isformed in the case 11 and the protrusion 25 is provided on the moldedcoil 2, it is also possible to provide the recess 24 in the molded coil2 and form the protrusion 25 on the case 11.

INDUSTRIAL APPLICABILITY

As has been described above, in accordance with the present invention,it is possible to finally integrate the molded coil and the solenoidmain body with each other after various operation processes; by finallyattaching the molded coil, the lead wire extending from the molded coilconstitutes no obstacle, and the assembly is facilitated, thus achievingan improvement in terms of operability.

1. A solenoid comprising: a molded coil composed of a coil of a pluralnumber of turns having a hole at its center; and a solenoid main bodyhaving a case covering the outer periphery of the molded coil, a movableplunger inserted into the hole at the center of the molded coil, and acenter post arranged in a direction in which the plunger is moved andattracted by a magnetic force generated by the coil, wherein there isprovided a snap ring for integrating the molded coil and the solenoidmain body into one, wherein the snap ring is mounted between a grooveformed in an outer peripheral surface of the molded coil and a grooveformed in an inner peripheral surface of the case, wherein an outerdiameter of the molded coil as measured at least on the outer side of aposition where the snap ring is mounted is substantially the same as aninner diameter of the case, wherein a peripheral section of the bottomof a groove formed in the outer peripheral surface of the molded coiland around which the snap ring is wrapped is noncircular, and wherein awall portion is provided which protrudes from the bottom of the grooveformed in the outer peripheral surface of the molded coil and aroundwhich the snap ring is wrapped and which constitutes a stopping betweenend portions of the snap ring.
 2. A solenoid comprising: a molded coilcomposed of a coil of a plural number of turns having a hole at itscenter; and a solenoid main body having a case covering the outerperiphery of the molded coil, a movable plunger inserted into the holeat the center of the molded coil, and a center post arranged in adirection in which the plunger is moved and attracted by a magneticforce generated by the coil, wherein there is provided a snap ring forintegrating the molded coil and the solenoid main body into one, whereinthe snap ring is mounted between a groove formed in an outer peripheralsurface of the molded coil and a groove formed in an inner peripheralsurface of the case, wherein an outer diameter of the molded coil asmeasured at least on the outer side of a position where the snap ring ismounted is substantially the same as an inner diameter of the case,wherein a peripheral section of the bottom of a groove formed in theouter peripheral surface of the molded coil and around which the snapring is wrapped is noncircular, and wherein a protrusion is providedwhich is spaced apart from the bottom of the groove formed in the outerperipheral surface of the molded coil and around which the snap ring iswrapped and which is situated on the outer side of a portion between theend portions of the snap ring.